Baffle means for heat exchanger, and method of fabrication thereof

ABSTRACT

A one-piece baffle member for use in the heat tubes of a horizontal fire tube boiler for spanning a part of the crosssectional area of the heat tubes in the portion thereof to which the heating medium normally gravitates to encourage deflection of the heating medium to a portion of the tubes to which it does not normally gravitate. The baffle member is stamped from generally flat sheet metal material having an elongated body portion extending longitudinally of a heat tube generally in the area of a diameter thereof, with a baffle portion bent upwardly from one end of the body portion extending transversely of the heat tube spanning the top portion of the heat tube. Feet portions are bent downwardly from the body portion for engaging the lower inside surface of the heat tube affording the sole support of the baffle member in the heat tube. The disclosure includes a method of fabricating the baffle member by stamping a blank therefore from a strip of sheet metal material.

nited States Patent [191 Phillips Nov. 19, 1974 1 BAFFLE MEANS FOR HEAT EXCHANGER,

AND METHOD OF FABRICATION THEREOF [76] Inventor: James L. Phillips, 2635 S. Avers Ave., Chicago, 111. 60623 [22] Filed: Nov. 3, 1972 [21] Appl. No.: 303,321

[52] U.S. Cl... 122/149, 110/97 D, 138/38 [51] Int. Cl. F22h 7/12 [58] Field of Search 122/149; 110/97 D; 138/38 [56] References Cited UNITED STATES PATENTS 977,927 12/1910 Bugnon 122/501 2,553,141 5/1951 Maynard... 138/38 X 2,641,206 6/1953 Stout 110/97 3,413,939 12/1968 Phillips 110/97 Primary ExaminerKenneth W. Sprague Attorney, Agent, or Firm-Coffee and Sweeney [5 7] ABSTRACT A one-piece baffle member for use in the heat tubes of a horizontal fire tube boiler for spanning a part of the cross-sectional area of the heat tubes in the portion thereof to which the heating medium normally gravitates to encourage deflection of the heating medium to a portion of the tubes to which it does not normally gravitate. The baffle member is stamped from generally flat sheet metal material having an elongated body portion extending longitudinally of a heat tube generally in the area of a diameter thereof, with a baffle portion bent upwardly from one end of the body portion extending transversely of the heat tube spanning the top portion of the heat tube. Feet portions are bent downwardly from the body portion for engaging the lower inside surface of the heat tube affording the sole support of the baffle member in the heat tube. The disclosure includes a method of fabricating the baffle member by stamping a blank therefore from a strip of sheet metal material.

11 Claims, 5 Drawing Figures BAFFLE MEANS FOR HEAT EXCHANGER, AND METHOD OF FABRICATION THEREOF BACKGROUND AND SUMMARY OF THE INVENTION This invention relates to heat exchangers and more particularly to an improvement in a baffle means for association with a boiler or the like.

Common heat exchanger structures utilize the comingling of mediums at different temperatures in order to produce a desired temperature in one of the mediums for purposes of heating or cooling. For example, gas, such as air, may be passed through liquid, such as water, so that one of the two fluids may be heated or cooled.

In horizontal fire tube boilers, a large heating chamber is formed inside a boiler shell which serves as a jacket for water to be heated. Heat tubes extend longitudinally of the shell and are in communication with the heating chamber. Suitable means are provided for circulating the heated air from the combustion chamber throughthe heat tubes to thereby heat the water in the shell. As the hot gases pass through the heat tubes, the water is heated and this heated water is fed to suitable radiating structures for heating areas remote from the boiler.

Commonly the medium which is initially heated or cooled for purposes of heat exchange with the second medium tends to follow a path which approaches the direction towards which such mediums would normally gravitate. For example, as the air is heated in the combustion chamber of a fire tube boiler, the hot air tends to flow to the uppermost fire tubes and some of the extreme lowermost fire tubes receive little of the heated air. In addition, in the fire tubes themselves through which the heated air does pass, it further tends to gravitate toward the upper half of each tube, reducing the efficiency of the heat transfer from each tube. As a result, hotter air must be fed through the boiler in order to obtain the desired heat in the water in the boiler jacket. This results in the exhaust structure or stacks being extremely hot, increasing fire hazard as well as increasing the pollution, by heat at least, of the surrounding external air.

This invention is directed, in brief, to the provision of a baffle means for insertion into the tubes of the heat exchanger so that a more efficient transfer of heat may be obtained which will also afford less extreme exhaust temperatures and thereby moderate the temperatures prevailing in the exhaust structure.

It is therefore a general object of this invention to provide an improvement in heat exchanger structures.

In the exemplary embodiment of the invention, a horizontal fire tube boiler has a plurality of generally horizontal, generally cylindrical, heat tubes mounted within a boiler shell, with a combustion chamber in'communication with the heat tubes for supplying heated gases thereto to heat water about the heat tubes by heat transfer. The baffle members are positioned in at least some of the heat tubes spanning a part of the crosssectional area thereofin the portion of the heat tubes to which the heating medium normally gravitates to encourage deflection of the heating medium to that portion of the tubes to which it does not normally gravitate. The baffle members each are stamped from a strip of sheet metal material to form a blank in the shape of an elongated body portion having a wider baffle portion at one end thereof and feet portions protruding outwardly from the sides thereof. The baffle portion is in the form of a semi-circular disc which is then bent upwardly for positioning transversely of a heat tube mating with and spanning the top of the cylindrical heat tube. The feet portions are bent downwardly from the flat body portion for engaging the lower interior surfaces of the heat tube affording the sole support of the baffle member in the heat tube. The flat body portion of the baffle member is disposed generally in the area of a diameter of the heat tube and the width of the body portion is less than the width of the heat tube to permit the heating medium to pass thereabout.

Other objects, features and advantages of the present invention will be apparent from the following description of the preferred embodiments illustrated in the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary longitudinal section view partially shown in side elevation of a horizontal fire tube boiler utilizing the baffle means of this invention;

FIG. 2 is a vertical section view taken along the line 2-2 of FIG. 1;

FIG. 3 is a partially broken vertical section through a heat tube with a side elevational view of the baffle means of this invention;

FIG. 4 is an end elevational view of the baffle means taken generally along the line 4-4 of FIG. 3; and

FIG. 5 is a plan view of a blank for forming the baffle means of this invention as stamped from a strip of sheet material shown in phantom.

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings, in FIG. 1 there is shown a boiler 10 similar to the boiler disclosed in my US. Pat. No. 3,238,928, entitled Boiler," issued Mar. 8, 1968. As disclosed therein, the boiler includes a burner 12 for providing a means for heating the water 14 within the boiler. The boiler is constructed in the usual fashion, comprising a substantially tubular boiler shell 16 enclosed at each end by front and rear disc-like upright tube sheets 18 and 20, respectively, to form a water jacket for containing the water within the shell.

The front tube sheet is enclosed in the area of the tire tubes by the front end plate or head 22 which is secured to front tube sheet by suitable fastening means such as bolts 23' threaded onto nuts 23a projecting outwardly from the front tube sheet. Rear end plate 24 encloses .the rear tube sheet and is secured to the boiler by suitfor servicing or the like with the assistance of handle 24b.

Burner 12 communicates with the interior of the boiler shell by means of a fire tube 25 which opens into a larger diameter combustion chamber of fire drum 26, positioned in the interior of the boiler shell between the tube sheets. Combustion takes place within the fire tube 25 and combustion chamber 26 to provide the heated gas for heating the water within the boiler shell. The generally segmental spherical configuration of the rear end plate 24 forms a closed chamber 27 lined with refractory material 27a which directs the heated air from the fire drum through the heat tube 28. As the heated air passes through heat tubes 28, the water surrounding the tubes is heated by the exchange or transfer between the two mediums. The air is exhausted through the front tube sheet by way of an exhaust bonnet 29 at the top of the front end plate 22 and directed to atmosphere through an exhaust flue or stack 30.

The boiler is provided with the usual supply and drain means, such as a water inlet 31 and water drain 34. A monitoring gauge 33 may also be provided for actuating suitable control means in response to boiler temperatures or other parameters.

As best illustrated in FIGS. 3 through 5, a one-piece baffle means, generally designated 40, is interposed in the fire tubes, preferably near the exhaust end thereof. It is to be understood that while this baffle means is shown in use in a horizontal fire tube boiler, that this application is not limited to such structures and that the concept of this invention is applicable to a wide variety of heat exchangers including those whose function is to produce cooling.

Referring to FIGS. 3 and 4, the baffle means 40 comprises a one-piece member fabricated from generally flat sheet metal material having a generally flat body portion 42 extending longitudinally within a heat tube 28 with a baffle portion 44 bent upwardly from one end of the body portion 42, as best seen in FIG. 3, to transversely span the heat tube in the top portion thereof. Normally, the heat tubes 28 are cylindrical and, thus, the baffle portions 44 would be shaped as generally semi-circular disc portions, as best seen in FIG. 4, mating with generally the top half of the heat tubes. The body portion 42, thus, will be disposed generally in a plane in the area of a horizontal diameter of the heat tube. However, the body portion 42 is shown in FIGS. 3 and 4 to be disposed slightly below the vertical center of the heat tubes. The precise disposition depends upon the parameters of the system.

The flat body portion 42 of the one-piece baffle member has a width less than the width of the heat tubes 28 and a pair of feet portions 46 are bent downwardly from the sides of the body portion for engaging the lower interior walls of the heat tubes 28 affording the sole support of the baffle members 40 in the heat tubes. Thus, the heating medium passing through the heat tubes is deflected by the baffle portions 44 around the sides of the body portions 42 of the baffle members. Preferably, the baffle portions 44 are bent to extend generally at right angles to the body portions 42, as seen in FIG. 3, and the feet portions 46 are bent at acute angles to the body portions, asseenrin FIG. 4.

The method of the present invention for fabricating the the one-piece baffle member 40 from generally flat pliable sheet material, such as metal, is best visualized by reference to FIG. 5 where it can be seen that a blank, generally designated B, is stamped from a strip S of the sheet material which is shown in phantom in FIG. 5. The blank B is shown in plan view in FIG. 5 and the body portion 42 is shown with the baffle portion 44 at one end thereof and the feet portions 46 protruding outwardly from the sides thereof. In this manner, the strip S need only be as wide as the inside diameter of the heat tubes 28. The baffle portion 44 is then bent along dotted lines 48 at a right angle to the flat body portion 42 for extending in one transverse direction to span the top part of the cross-sectional area of a heat tube 28. The feet portions 46 are bent along dotted lines 50 at an acute angle to the flat body portion 42'for extending in an opposite transverse direction to support the baffle member in a heat tube. The stamping of the blank B from the strip S of sheet material and the bending of the baffle portion 44 and feet portions 46 may be performed in a progressive press having a series of punching and forming dies or stations. The baffle portion 44 and feet portions 46 may be bent from the body portion 42 simultaneously at a single station or, if preferred, the bending steps may be performed seriatim either bending the baffle portion 44 first or the feet portions 46 first.

It should be understood that the one-piece baffle member 40 may be positioned in a heat tube with the heating medium flowing in either direction through the tube relative to the endwise positioning of the baffle member. However, should the heating medium be flowing in the direction of arrow A (FIG. 3) and the baffle member 40 be positioned as shown in FIG. 3, the mass of the body portion 42 between the feet portions 46 and the end 52 of the body portion must be sufficient to counteract the weight of the baffle portion 44 and that part of the body portion 42 between the baffle portion and the feet portions 46. In addition, should sufficient force be created by the flow of the heating medium striking the inner face of the baffle portion 44, the mass of the body portion 42 between the end 52 thereof and the feet portions 46 must be sufficient also to counteract that additional force so as to prevent the baffle member from pivoting about the feet portion 46 in the direction of arrow C (FIG. 3). The drawings are merely representative of the disclosure.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom; as some modifications may be obvious to those skilled in the art.

I claim:

1. In combination, a fire tube boiler having a plurality of generally horizontal heat tubes mounted within a boiler shell and a combustion chamber in communication with the heat tubes for supplying heated gases thereto to heat water about the heat tubes by heat transfer, and baffle means in at least some of said heat tubes spanning a part of the cross-sectional area thereof in the portion to which the heating medium normally gravitates to encourage deflection of the heating medium to that portion of the tubes to which it does not normally gravitate, the baffle means each being comprised of a one-piece member having a body portion extending longitudinally of a heat tube, a baffle portion extending upwardly from one end of said body portion transverselyof said'heat tube spanning the top portions of the heat'tube, andfeet means extending downwardly from said body portion for engaging the lower portions of the heat tube affording the sole support of the baffle member in said heat tube.

2. The combination of claim 1 wherein said onepiece baffle member is fabricated from generally flat sheet material.

3. The combination of claim 2 wherein the body portion of said baffle member is generally flat and extends generally horizontally in said heat tube.

4. The combination of claim 3 wherein said body portion is disposed generally in the area of a diameter of said heat tube.

5. The combination of claim 4 wherein said heat tube is generally cylindrical and said baffle portion is shaped 6 of said baffle portion mates with generally the top half of the heat tube.

9. The combination of claim 8 wherein said heat tube is generally cylindrical and said baffle portion is shaped as a generally semi-circular disc portion.

10. The combination of claim 1 wherein said body portion between said feet means and the end of the body portion opposite said baffle portion is of a mass of sheet material sufficient to counteract the weight of the baffle member, including said baffle portion. on the opposite side of the feet means.

11. For use in a fire tube boiler having a plurality of longitudinally extending heat tubes, a one-piece baffle member having a body portion extending longitudinally of a heat tube, a baffle portion extending upwardly from one end of said body portion transversely of said heat tube spanning the top portions of the heat tube, and feet means extending downwardly from said body portion for engaging the lower portions of the heat tube affording the sole support of the baffle member in said heat tube. 

1. In combination, a fire tube boiler having a plurality of generally horizontal heat tubes mounted within a boiler shell and a combustion chamber in communication with the heat tubes for supplying heated gases thereto to heat water about the heat tubes by heat transfer, and baffle means in at least some of said heat tubes spanning a part of the cross-sectional area thereof in the portion to which the heating medium normally gravitates to encourage deflection of the heating medium to that portion of the tubes to which it does not normally gravitate, the baffle means each being comprised of a one-piece member having a body portion extending longitudinally of a heat tube, a baffle portion extending upwardly from one end of said body portion transversely of said heat tube spanning the top portions of the heat tube, and feet means extending downwardly from said body portion for engaging the lower portions of the heat tube affording the sole support of the baffle member in said heat tube.
 2. The combination of claim 1 wherein said one-piece baffle member is fabricated from generally flat sheet material.
 3. The combination of claim 2 wherein the body portion of said baffle member is generally flat and extends generally horizontally in said heat tube.
 4. The combination of claim 3 wherein said body portion is disposed generally in the area of a diameter of said heat tube.
 5. The combination of claim 4 wherein said heat tube is generally cylindrical and said baffle portion is shaped as a generally semi-circular disc portion mating with generally the top half of the heat tube.
 6. The combination of claim 3 wherein the width of said body portion is less than the width of said heat tube.
 7. The combination of claim 6 wherein said feet means extend outwardly and downwardly from the side edges of said body portion.
 8. The combination of claim 2 wherein the periphery of said baffle portion mates with generally the top half of the heat tube.
 9. The combinatIon of claim 8 wherein said heat tube is generally cylindrical and said baffle portion is shaped as a generally semi-circular disc portion.
 10. The combination of claim 1 wherein said body portion between said feet means and the end of the body portion opposite said baffle portion is of a mass of sheet material sufficient to counteract the weight of the baffle member, including said baffle portion, on the opposite side of the feet means.
 11. For use in a fire tube boiler having a plurality of longitudinally extending heat tubes, a one-piece baffle member having a body portion extending longitudinally of a heat tube, a baffle portion extending upwardly from one end of said body portion transversely of said heat tube spanning the top portions of the heat tube, and feet means extending downwardly from said body portion for engaging the lower portions of the heat tube affording the sole support of the baffle member in said heat tube. 